The present invention relates to a device for respiratory assistance allowing emergency medical care to be provided efficiently to a patient who is in danger of dying.
It is known, for example in the case of cardiac arrest, to attempt to resuscitate a patient by massage and, in order to increase the efficacy of this massage, said patient is administered a vasoconstrictive medicine such as adrenaline. This medicine is administered either intravenously or through an endotracheal tube. In the first case, the medicine is relatively slow to arrive at the lungs, while in the second case the medicine disperses and does not necessarily reach said lungs.
Moreover, document EP-0 390 684 has already disclosed a device for respiratory assistance in the form of a tube which can be introduced into the mouth or the nose of a patient and which, in addition to the main channel formed by the tube, comprises at least one auxiliary channel, for example formed in the wall of said tube, permitting injection of a jet of respirable gas (oxygen, air, or mixture of oxygen and air) intended to ventilate the patient, these auxiliary channels opening into the main channel in proximity to the distal end of the latter.
To ensure that the jets of respirable gas do not directly strike the mucosa of the patient under ventilation, risking traumatizing said mucosa on account of their kinetic energy, provision is made, in this known device, that at least the distal end of said auxiliary channels opening into the main channel is parallel thereto and that, opposite the distal orifice of each auxiliary channel, there are deflection means for deflecting said jets of respirable ventilation gas toward the inside of said main channel.
Thus, the jets of respirable gas passing through said auxiliary channels are deflected toward the axis of the main channel when they enter the latter. Experimental measures have shown that, downstream of said deflection means, a pressure zone of oblong shape forms inside said main channel, starting at the points where said auxiliary channels open into the main channel, and continuing in the axial direction along the axis of said main channel with progressive reduction in its cross section, so as to occupy only the central part of the main channel, but that the pressure of said jets of respirable gas drops downstream of said zone of high pressure and the jets of gas pass at low pressure through the distal orifice of the tube. Experience has also shown that, downstream of the distal outlet of the tube, the pressure is low and is maintained constant throughout the respiratory space. This pressure is dependent on the flowrate of respirable gas in the auxiliary channels. Consequently, with the device for respiratory assistance in accordance with the above document, it is possible for example to supply oxygen or a mixture of air and oxygen directly to a patient""s lungs, at the level of the carina, and thereby eliminate the dead space which exists in the other known probes and which is approximately a third of the total respiratory volume for an adult and about half for premature neonates. The elimination of this dead space corresponds to an increase in performance of the respiratory cycle of more than 25% in all patients and of nearly 50% in certain cases.
The device in document EP-0 390 684 is therefore particularly advantageous.
The object of the present invention is to improve this known device in order to allow it to administer medicines efficiently, not only to solve the problem of administering a vasoconstrictor in the event of a cardiac emergency, as was mentioned above, but also in all cases where this is useful.
To this end, according to the invention, the device for respiratory assistance comprising a tube which forms a main channel and which is intended to be connected via its distal end to an airway of a patient so that said main channel connects said patient""s respiratory system to the outside, said device further comprising at least one auxiliary channel which is connected, at its proximal end, to a source of respirable gas in order to be able to insufflate a jet of this respirable gas into said respiratory system and whose distal end opens into said main channel in proximity to the distal end of the latter, deflection means for deflecting said jet of respirable ventilation gas in the direction of the axis of said main channel being provided opposite the distal orifice of said auxiliary channel in such a way that, downstream of said deflection means, a pressure zone of oblong shape forms inside said main channel, starting at said distal orifice and continuing in the distal direction along the axis of said main channel, with progressive reduction of its cross section as it moves away from the inner wall of said main channel and comes to occupy only the central part of the latter, is distinguished by the fact that said tube comprises, downstream (relative to said jet of respirable gas) of said deflection means, at least one distribution orifice which opens into said main channel opposite said oblong pressure zone and which can be supplied with a medical fluid.
Thus, by virtue of the present invention, the medical fluid, which can be a gas or liquid, is nebulized and delivered directly to the lungs of the patient under ventilation exactly like the respirable ventilation gas, while said lungs are inflated by means of this ventilation. The injection of the medical fluid thus affects the totality of the surface of said lungs, so that said fluid can have the maximum efficacy.
Said orifice for distribution of medical fluid is preferably connected to the proximal end of said tube via a channel which is provided within the thickness of said tube and by way of which it is supplied with medical fluid.
In the case where, in order to avoid using a source of respirable gas at high pressure, the device according to the present invention comprises, as is described in the document U.S. Ser. No. 09/387,790, a ring arranged in said main channel downstream (relative to said jet of respirable gas) of said deflection means and surrounding said oblong pressure zone and at least partially obturating the peripheral space of said main channel located between said inner wall of the latter and said oblong pressure zone, it is advantageous that said ring is arranged between said distribution orifice and said deflection means.
Moreover, in order to further increase the efficacy of the device according to the present invention, it is preferable that the supply of medical fluid to said distribution orifice is interrupted during the patient""s exhalations, so that said medical fluid is introduced into the latter""s lungs only during inhalations.